Central-supply telephone system.



"110.780,001. 0 PATBNTED 10.11.24, 1905.

' W. W. DEAN.

CENTRAL SUPPLY vTELBPHOM.' SYSIBM.

APPLICATION FILED MAB. 22, 1901.

No. '2530,60'1.V

g UNITED STATES 'Patented January 24, 1905.A

PATENT OFFICE.

WILLIAM`VW- DEAN, OF CHICAGO, "ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

CENTRAL-SUPPLY `TELEFHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 780,601, dated January 24, 1905.

Application filed. March 22, 1901. Serial No. 52,275.

`concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a central -supply telephone system-that is, a telephone system of the class in which the Vmicrophones at the,

'substations are energized from a source of electricity located at the central station.

In'accordance with the present invention I provide asource of electricity at the central station adapted to send current over the limbs of the two connected telephone-'lines in series,

said source being associated with a repeatingcoil interposed between the lines insuch amanner that the talkingLcurrents may traverse each line independently, corresponding currents being propagated in the connected line through the agency of the repeating-coil.v

Il have illustrated my invention in the accompanying drawings, in whichl Figure 1 is a' diagram showing two telephone-lines connected together with the apline-springs d and Z2 of lthe switch-socket.A

Any preferred form of individual indicator may be employed,and'I have illustrated an indicator c and a battery r', connected between contacts 2 and 3, normally resting againstlinesprings el and d?, respectively, and separated therefrom'upon the insertion of the plug. At

the substation the usual microphone f, receiver f', and switch-hook f2 are provided,

the switch-hook normally resting against contact 7 and adapted when the receiveris removed from the hook to engage contact 8. The bell f3 and condenserZ are bridged between the two limbs of the telephone-line.

The apparatus of substation B is similar to that of substation A, and like parts are indicated by the same reference characters.

I have shown the central-station apparatus as consisting of the usual answering-plug p, having' tip p and sleeve p2, the former connected with strand t and the latter with strand s. The calling-plug 0 is provided with the usual tip 0 and sleeve 02, the former being `connected with strand t and the latterk with strand s. Between the strands t s and t s are the repeating-coils 'w and w', the coil fw having two windings fw2 w3 and the coil w having two windings wiand w. The energizingbattery r is connected between the windings fw2 and w3, and a bridge 3, containing a condenser Z, connects the united ends oi' the windings wi and w5 with the united ends of windings cc2 and w3. In the strand s is the magnetcoil of a signal-controlling electromagnet Vor relay It, around which is a path it', permitting the passage of talking-currents, while limiting the passage of continuous currents. Likewise inthe strand cis the winding of an electromagnetic, having asimilar path lc around the same. Non-inductive resistances, condensers; or similar devices may be employed in the paths 7L- and 7c. The magnet /r controls an arm In, normally resting against contacts 12 and 13,'contact 12 being connected through resistancewith the conductor 3. tact `1-3is connected through signal-lamp mf and with contact 11, lwhich is adapted to rest against spring m2 0i' a plug-seat switch controlled by the plug p, the spring m2 being connected by conductor 4 with onepole of the battery r. Likewise the magnet controls arm e, which normally rests against contacts 14 and 15, the former being connected through resistance with conductor 3 and the latter The conbeing connected through lamp c with contact Y tween the strands t and s in the usual manner. l

The essential features of the apparatus are illustrated in diagram in Fig. 2. When the subscribers are connected for conversation, the current from battery o passes through Winding w3, thence through the apparatus at the substation B, through windings Q05 and 104, and through the apparatus of substation A, and then passes through Winding 102 back to the opposite side of the battery. The current from the battery r thus traverses the limbs of the two connected lines in series. The talking-currents, however, propagated from substation A traverse windings @02 and a# through the Abridge 3 and induce corresponding currents in windings w3 and w, which pass to substation B. In a similar manner talkingcurrents propagated at substation B pass to substation A. The condenser Z in the bridge 3 permits the passage of the talking-currents, while preventing the flow of the current from battery r. The voice-currents are thus confined or localized in each line-circuit and circulate independently therein. The 'particular location of the bridge 3 is not essential so long as it connects the ends of the repeatingcoils with the opposite side of the talking-circuit. VVhilel have illustrated two repeatingcoils w and w', it will be understood this is for the purpose of balancing the system and that one repeating-coil may be employed, if desired. While the battery r is shown as connected between the windings of one of the repeating-coils, this particular location of the battery is not essential.

It will be noted that with thel structure as shown in Fig. Q the hanging up of the telephone of either of the connected subscribers opens the circuit of battery r, and if the battery '7' be depended upon for actuating the supervisory signals at the central station one of the connected subscribers could not send in a further call until the operator had removed the plugs. In order that either of Vtwo connected subscribers may in the usual manner signal the operator for another connection before the connecting-plugs are withdrawn, l provide the auxiliary apparatus particularly illustrated in Fig. 1. If it be as- .sumed that subscriber A desires to converse with subscriber B, he lifts his telephone from its hook, thereby closing the circuit of battery r through indicator c and the limbs of the telephone-line in the'customary manner. The indicator c is thus actuated, and the operator thereupon lifts the plug p from its seat and inserts the same in the switch-socket belonging to line A. The removal of the plug from its seat permits the spring m2 to engage contact 11. Contacts o2 and .10 remain separated until the plug 0 is removed from its seat. The insertion of the plug p in the switchsocket closes the circuit of battery /r over conductor 4, contacts m2 and 11, cond uetor 9, spring' o, contact 14, resistance ne', winding wf, magnet It, strand s, limb a, limb a., strand t, and winding 102 to the opposite side of the battery. Magnet /L is thus energized and lifts spring m from contacts l2 and 13. rlhe current from battery rbeing thus sent through the apparatus at the substation, the operator may connect her telephone in circuit in the usual manner and receive the number of the called subscriber. Learning that subscriber B is called for, she lifts plug 0 from its seat and inserts the same in the switch-socket belonging to subscriber B. Contacts c2 and l() are thus closed together. Having inserted the plug o, the operator sends rin ging-current to substation B in the usual manner. When subscriber B responds and lifts his telephone from its hook, the circuit of battery r is closed over the limbs of the two telephone-lines in series, as shown in connection with Fig. 2, and magnet is energized to lift spring n out of contact with contacts'14 and 1 5. rlhe circuits through conductors 4 and 5 thus both remain open while the subscribers are in conversation.

When the subscribers have completed their conversation, they hang up their telephonereceivers and the circuit of battery fr is interrupted, thereby denergizing the magnets la and /ff and closing the circuit of battery lr, through the lamps m' and c. The circuit of battery a' through the lamp m may be traced over conductor 4, contacts fm, and 11, lamp m, spring m, conductor 6, contacts 10 and o, and conductor 5 back to the battery. The circuit through lamp fu may be traced from battery a' over conductor 4, contacts m2 and 11, conductor9, spring ci, lamp o', contacts 10 and '02, and conductor 5 back to the battery. The lamps being lighted to indicate to the operator that the conversation has been completed, she withdraws the plugs p and 0 and returns the same to their respective seats. The circuit through the lamps fm/ and fu are thereupon opened at the contacts by the plug-scat switches. Assuming that before the plugs are removed subscriber A desires a reconnection with another party, he vibrates his switchhook in the usual manner. Magnet lz, is thus alternately energized and denergizcd to open and close the circuit through the lamp m to alternately light and extinguish the same. The circuit of battery 7' thus controlled by subscriber A may be traced over conductor 4 through contacts m2 and 1l, cond uetor 9,spring o, contact 14, (magnet/t' being denergized by the hanging up of the receiver of subscriber B,) resistance winding wi strand s, limb a', limb a, strand t, -winding wz back to the battery. Each subscriber may thus control IOO the-circuit through' his clearing-out indicator independently oi' the connected subscriber,v and while i the energizing-battery is connected in series with the connected lines so long asv the same are connected for conversation the Io dicatOI'. L

y Having'described my invention, what Iv claim as new, and desireto secure byLetters Patent is- 1.. rlhe combination with a pair of telephonelines, ofL means for uniting the same for conversation through a repeating-coil bridged between the two limbs of the talking-circuit, and an energizing source or' electricity adapted to send vcurrent through'the two limbs of the two lines in series. substantiallyfas described.

2. The combination with a pair of telephonelines, of means for uniting the same for conversation through arepeating-coil having its windings` bridged between the two sides of the talking-circuit whereby the talking-currents may traverse each line independently,an energizing source oi-xelectricity adapted to send current through the two limbs of the two lines in series, and. meansfor preventing the energizingcurrent from passing through the bridge for the talking-currents containing the windings of the repeating-coil, substantially as described.

, 3. The combination withapair oi telephonelines, of means for uniting the same for conversation through a repeating-coil, and an energizing source of electricity adapted to send current through the two limbs of the two lines and through the primary and secondary windtially as described. Y

4L. The combination with apair of telephonelines, of means for uniting the same for conversation through a repeating-coil, the ends of the primary and secondary windingsl of said repeating-coil beingjoined together, van energizing source of electricity adapted to -send current through the limbs of the two telephone-linesand through said primaryand secondary windings inseries and av bridge for the talking-currents connecting the united ends of said windings with the opposite side of thetalking-circuit, substantially as described.

5. The combination with a pair of telephonelines, of means for uniting the same for conversation lthrough a. repeating-coil, the primary and secondary windings of said coil being connected together,an energizing source of electricity adapted to send current through the limbs of said line, and said primary and secondary windings in series, and a bridge containing a-condenser connecting the united ends of saidY windings with the opposite side of the talking-circuit, Asubstantially as described. 5

ings of said repeating-coil in series, substan- 6., The combination with a pair of telephonel lines, of means l.for uniting the same for conversation through a repeating-coil, an energizing source of electricity connected between the primary and secondary windings of said coil having united ends, and adapted tosend current through said primary and secondary windings and the limbs of the two lines in series, and-a bridge for the talking-currents joining the united ends of said windings with the opposite side of the talking-circuit, substantially as described. 7 The combination with a pair of telephonelines, and means'ior uniting the same for conversation, through a pair of repeating-coil windings having united ends, an energizing source of electricity connected between vthe primary and secondary windings of one pair and adapted to send current through the limbs of the two lines and the windings of the two pairs in series, and a bridge for the talkingcurrents connecting the united ends of one `.pair of windings with the united ends of the other pair of windings, substantially as described.

8. The combination with a pair of telephonelines, of a charging source of electricity adapted to send current over the two limbs of the two llines in series, and means controlled by g each telephone-line for connecting the other telephone-line in a'complete circuit with said source loi" electricity, substantially as described. 9. The combination with a pair of telephonelines, cfa charging source of electricity adapted to send current over the limbs of the two lines in series,l and a switch at each substation and additional means for connecting the other telephone-line in a complete circuit with said source of' electricity, substantially as described. 10. The combination with a pair of telephone-lines, of a charging source of electricityl -adapted to send'current over the limbs of the two lines in series, a pair of relays at the central station one lndlvidual to each llne during a connection, means at each substation for controlling the relay corresponding to said line, and means controlled by the relay of each line for closing the other line in a complete circuit withy said source oi"electri'city, substantially as described.

ll. rlhe combination with a pair of-telephone-lines, of a pair of cord connectors for uniting the same for conversation, a charging source of electricityincluded in series with one of the strands of said cord connectors, and

means controlled by each telephone-line'for connecting said source of electricity betweenl ythe two strands of the cord connectors and in a complete circuit with the other telephoneline, .substantially as described.

12. The combination with a pair of telephone-lines,.of means for uniting the same for conversationincludinga repeating-coil bridged between the two sides of the talking- IOO circuit, and further means for sending current from the central olice through the two sides of the two lines in series, substantially as described.

13. The combination with a pair of telephone-lines, of means for uniting the same for conversation including a repeating-coil having its windings bridged between the two sides ot' the talking-circuit whereby the talking-currents may traverse each line independently, and means for sending an energizing-current of electricity from the central oiiiee through the two sides of the two connected lines in series, and additional means for preventing the energizing-current from passing through the bridge for the talking-currents containing the windings of the repeating-coil, substantially as described.

14. The combination with a pair of telephone-lines, of means for uniting the same for conversation including a repeating-coil, means for sending an energizing-current ot' electricity through the two limbs of the two lines and through the primary and second ary windings of said repeating-coil in series, and means to con tine the voice-currents independently to each line-circuit, substantially as described.

15. The combination with a pair of united telephone-lines, a current source at the central oce arranged to send current over the two sides of the complete talking-circuit of the united lines in series, and means for localizing the voice-currents in each line of the united pair, substantially as described.

16. The combination with a pair of telephone-lines, oi' a current source at the central oflice adapted to send current over the limbs of the two lines in series, and means controlled from one substation for connecting the said current source in a circuit individual to the other line, substantially as described.

17. The combination with a pair of telephone-lines, of a charging source of electricity adapted to send current over the limbs of the two lines in series, and means controlled from one substation for causing current from said source to flow in a circuit individual to the other telephone line, substantially as described.

18. The combination with a pair of telephone-lines, of a current source of electricity at the central ofiice adapted to send current over the limbs or' the two lines in series, and means controlled from each substation for causing current from said source to ilow in a circuit individual to the telephone-line of the other substation, substantially as described.

19. The combination with a pair of telephone-lines, of a charging source ot' electricity adapted to send current over the two limbs of the two lines in series, means controlled by each telephone-line for connecting the other telephone-line in a complete circuit with said source of electricity, and a supervisory-signal-controlling electromagnet associated with each line and controlled during the connection and when one subscribers line is open by the current in said complete circuit, substantially as described.

20. The combination with a pair of telcphone-lines, of a charging source of electricity adapted to send current over the limbs of the two lines in series, a pair ot' magnets at the central station, one individual to each line during a connection', means at each substation for controlling the relay corresponding to said line, means controlled by the relay of each line for closing the other line in a complete circuit with said source of electricity, and a supervisory signal controlled by each of said magnets, substantially as described.

21. The combination with a pair of telcphone-lines, of a pair of cord connectors for uniting the same for conversation, a charging source of electricity included in series in one of the strands of said cord connectors, means controlled by each telephone-line for connecting said source of electricity between the two strands ot' the cord connectors and in a complete circuit with the other telephone-line, and supervisory signals associated with each line and controlled by current from said source, substantially as described.

22. The combination with a pair of telephone-lines united for conversation, of supervisory-signal-controlling magnets associated with said lines, a signal controlled by each magnet, a source of current adapted to send current over the two lines in series during conversation, said magnets being located in the path ot' said series current and energized thereby during conversation, and each magnet being energized by current from said source over its own line only when the circuitot the other united line is opened, substantially as described.

23. The combination with a pair ol' united telephone-lines, of an inductive device to unite said lines for conversation, a current source at the central oiiice arranged to send current over the two sides oi' the complete talkingcircuit of the united lines in series, means for localizing the voice-currents in each line of the united pair, and a supervisory signal associated with each of the united lines and controlled from said source, substantially as described.

24. The combination with a pair ol telephone-lines, of a current source at the central ottice adapted to send current over the limbs of the two lines in series, means controlled from one substation for connecting said current source in a circuit individual to the other line,andasupervisory-signal-controllingmagnet for each line in the path of current in series over the line when current so i'lows and in the path of current individual to the lines when the other line is open, substantially as described.

25. In a telephone system, the combination IOO with a pair of telephone-lines, of means for uniting the same for conversation, a source of current adapted to send current over the two sides of the two lines in series, means for localizing the voice-currents in each of the lines, a relay associated with each line, a local circuit controlled by each relay, a supervisory signal in each local circuit,and means for normally opening said llocal circuit at another point and for closing the same during connections, substantially as described;

26. In a telephone system, the combination with a pair of telephone-lines, of a cord-circuit including connecting-plugs for uniting the same for conversation, a source of current adapted to send current over two sides of the lines in series during conversation, means for localizing the voice-currents in each of the lines, a relay associated with each end of the cord-circuit, a local circuit controlled by eacli relay, a supervisory signal in each local circuit, and plug-seat switches for the said plugsl to normally open said circuits, substantially as described.

27. In a telephone system, the combination with a pair of telephone-lines, of means for uniting the same for conversation, a source of current adapted to send current over the two sides of the two lines in series, means for localizing the voice-currents in each of the lines, a relay associated with each line and adapted to include said source of current in a circuit individual to the other line, a local circuit for each'relay, a supervisory signal in each local circuit, said local circuits and individual circuits being completed through normal contacts of said relays, substantially as described.

28. In a telephone system, thecombination with a pair of telephone-lines, of a cord-circuit including connecting-plugs for uniting the same for conversation, a source of current associated with the cord-circuit adapted to send current over the two' sides of the two lines in series during conversation and over each line independently when the other line is not in use, means for localizing the voicecurrents in each of the lines, a relay associatedl each end, a source of current connected with the cord-circuit and adapted to send current over the two sides of the two lines in series, means for localizing the voice-currents in each of theA lines, a relay associated with each end of the cord-circuit, a local circuit controlled by each relay, a supervisory signal in each local circuit, plug-seat switches for each of the plugs, the contacts of both of said switches being included in each local circuit, substantially as described.

30. In a telephone system, the combination with a pairlof telephone-lines, of a common source of current at the central oliice, means to include said source in series in the metallic circuit of said two lines during conversation,

a condenserpto permit individualizing theI voice-currents in each line, supervisory signals at the central oiice one for eacli line, a supervisory relay for each line, and local circuits for said signals, said local circuits including a short circuit of said condenser controlled by the corresponding relay-contacts and other switch-contacts, substantially as described.

In witness whereof I have hereunto subscribed my name in the presence of two witnesses.

WILLIAM W. DEAN. Witnesses:

MELANCTHON R. NYMAN, W. CLYDE JoNEs. 

